1. Field of the Invention
The present invention relates to a relay apparatus for relaying communication between wireless terminals and a wired network, and in particular, to a relay apparatus, a relay method, and a relay program for ensuring the quality of communication to be relayed, and a communication system including the relay apparatus.
2. Description of Related Art
Recently, for example, as in an IP telephone via a wireless LAN, a mobile terminal that performs a telephone conversion via wireless communication has become widespread. The mobile terminal that performs a telephone conversation via wireless communication enables a telephone conversation with a wired network by performing wireless communication with a relay apparatus (e.g., an access point of a wireless LAN, etc.). In such a communication form, mobile terminals are present in a communication area of a relay apparatus, whereby simultaneous telephone conversations by the mobile terminals occur. In this case, those mobile terminals share a communication bandwidth available in the relay apparatus, and perform communication respectively. Therefore, in the case where the number of mobile terminals that perform telephone conversations simultaneously via one relay apparatus increases, the communication bandwidth becomes insufficient. Consequently, at a mobile terminal, delays in audio communication from a terminal on a partner side is increased, and a noise such as a sound break occurs. This problem may occur in the case of communicating data such as music or a moving picture by streaming, as well as in the case of a telephone conversation. In General, the realtime communication to transmit streaming data as in a IP telephony service, a music distribution, a movie distribution, and the like, the shortage of a communication bandwidth in the relay apparatus degrades communication quality.
In order to prevent the shortage of a communication bandwidth in a relay apparatus, for example, a method has been adopted for rejecting the starting of a telephone conversation via the relay apparatus when the amount of a communication bandwidth available in the relay apparatus is not sufficient. Furthermore, a method has also been proposed, in which a call control apparatus receives traffic information from a relay apparatus at a constant interval, and controls the acceptance/rejection of communication to be relayed by the relay apparatus based on the received traffic information (e.g., see JP 2003-284144 A). The call control apparatus restrained making a new call to be relayed by the relay apparatus consuming large amount of traffic bandwidth when the usable bandwidth is already full.
However, in the above-mentioned conventional example, a multimedia type included in communication to be relayed by the relay apparatus has not been considered. Therefore, even in the multimedia communication which contains both audio and video streams, the relay apparatus was not able to perform a relay considering multimedia types (e.g., a preferential relay only for an audio stream). Because recent wireless terminals can handle multimedia communications, such relay apparatus should consider those multimedia types.